CA1088901A

CA1088901A - Method of manufacturing keyboard buttons

Info

Publication number: CA1088901A
Application number: CA296,004A
Authority: CA
Inventors: Robert W. D. Mitchell; James H. C. Purdie
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1977-02-24
Filing date: 1978-02-01
Publication date: 1980-11-04
Also published as: BR7800618A; JPS53125119A; DE2807843A1; GB1521435A; JPS5840517B2

Abstract

METHOD OF MANUFACTURING KEYBOARD BUTTONS
Abstract The invention provides a photo-projection and develop-ment technique which is suitable for computer controlled mass production of low cost keyboard buttons with coloured characters.
The process comprises assembling blank keyboard but-tons with the surface on which a character is to be de-posited in a predetermined orientation. Then, after cleaning, the character surface is coated with a layer of radiation sensitive material. Finally the layer is exposed to provide a latent image of a desired charac-ter, developed to give the character a permanent image, and lastly coated with a protective layer.

Description

FIELD OF THE INVENTIO~I
ThiC invention relates to keyboard buttons and to keyboard button manufacturing processes.
PRIOR ART
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~eyboard buttons are required in large numbers for 20 assembly in keyboards for data processing terminals and for typewriters. The keyboard buttons are mainly pro-duced at the present by three methods.
- The first method produces keyboard buttons which are molded, ready for use. The process used is known as a

2-shot molding, that is, the outer shell is molded to the correct colour and contours with the required characters ' molded into the top face, the second shot molds the inter-` nal features of the button and fills the characters which are connected to the inside of the shell.
A disadvantage of this method is that, as hundreds of different characters are required for the various languages . - ~ .. , . . . .,~ , .:

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~-1 and types of keyboards, the tooling and labor costs for this - ¦ 2 method are considerable.
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; l 3 The ~econd method uses blank buttons which are mainly produced by the 2-shot method but as the name implies, no ~`5 characters are molded on the top face. The required characters 6 are engraved and colored with a wax or paint filter.
The blank buttons are also used with other me-thods to '`8 produce characters such as:
g A transfer printing process where a rubber pad is lowered on to a previously inked die having the required characters.
11 The pad with the "wet ink" characters impressed on it is '' 12 positioned over the component and lowered to transfer the 13 characters .- .
14 Another method is hot foil stamping using a die containing ~ 15 the needed characters which is heated and usually mounted on a ;' 16 vertically moving die head on a spindle. The required color is `~b 17 obtained by interposing a colored foil between the button and the ' 18 die-head and lowering the die so that the foil contacts the button.
' 19 Local fusion takes place between the button and the foil and the color in the shape of the characters is transferred.
'~ 21 The third method uses button shells which are moldings ~;i` 22 taken from the first shot stage of the 2-shot moldin~ process.
- -23 The characters are engraved and the button completed by molding 24 the second shot. 'This method is used because the top surface of the button is textured which causes problems if wax/paint l 26 fillers are used and, due to low quantity of buttons needed, "!' 27 a unique first shot molding tool (with characters) is not ' 28 economic.

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1 A major disadvantage of -the Eoregoin~ methods is that it is 2 not economic to use the same method used to produce keyboard buttons

3 in-large numbers having commonly used characters for produciny '; 4 keyboard buttons in relatively small numbers having rarely used characters.
. 6 013Jl~CTS OF T~IE INV:E:NTION
7 In view of the foregoing difficulties and shortcominys ~-~ 8 with the prior art, it is an object of this invention to provide 9 an improved manufacturing process for depositing characters on ~ 10 keyboard buttons.
- 11 A further object of the invention is to provide an improved -- 12 process for creating different colored characters on keyboard .
13 buttons in a permanent and wear-resistant structure.

14 Still another object of the present invention is to provide an improved keyboard button having wear-resistant colored . .~. 1.6 characters thereon.
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17 SU~RY

18 According to the present invention, an improved keyboard 19 button manufacturing process for depositing characters on keyboard buttons comprises asse~bling blank keyboard buttons, 21 each having a surface on which a character is to be deposited, c 22 with the surface in a predetermined orientation, cleaning 23 said surface of each button chemically, coating said surface 24 of each button with a layer of radiation sensitive material, exposing said surface of each button to radiation to provide 2 6 a latent image of a selected character, developing the 27 exposed layer to provide the selected character, and coating 28 each character bearing surface with a transparent protective 29 layer.

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1 According to another aspect the invention comprises a ¦2 keyboard bu-tton produced by the above manufacturing process.
.. i 3 En,bodiments of tlle present invention use photGsensitive .4 materials commonly known as photoresists which are light : 5 sensitive polymeric materials. The materials used herein are ,6 called "negative/positive".resists by analogy to photographic ~ 7 terminology. Unexposed/exposed resist film is "developed"
.- 8 (dissolved away) by a "developer" (solvent, usually an alkali) 9 to leave uncovered areas.
Materials of this type, together with resist dyes and 11 pigments for coloring resists are available from many chemical , 12 manufacturers, for example, Shipley Company Inc., Kodak Ltd., - 13 Thiokol Corporation, Philip A. Hunt Chemical Corporation, 14 Minnesota Mining & Manufacturing Co., Du Pont de Nemours & Co.
Some of these companies issue publications describing the 16 properties of their materials to which a reader may refer.

.~, . . _ ........... .. _ ~;. 18 In order that the invention may be more readily understood, 19 reference will now be made; by way of example to the accompanying drawings in which:
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. 21 Figures lA to lE illustrate shapes of keyboard buttonsO
~::22 Figure 2 illustrates characters required on keyboards . :
~t 23 for Germany, Greece, Hungary and Hong Kong.
.~ 24 Figure 3 illustrates characters required on keyboards for l~ 25 Farsi, Mathematical, Technical and Copperplate Gothic.
r., 26 ~ Figure 4 shows in block form the steps in a manufacturing 27 process producing keyboard buttons embodying the present 28 invention.
.. 29 Figure 5 shows.an optical projection system for use in the 30 process of Figure 4.

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1 DETAILED SPI.CIFICATION
2 Fic;ures 'A to lE illustrate the shapes of some keyboard 3 buttons at present in use. For each, a plan view is shown

4 including the characters 20 on the button and a side view to show the shape of the surface carryiny the characters. It wiLl 6 be noted that Figure lA shows a button with a flat surface 21, -~ 7 whereas Figures lB, lC and lE show a concave surface 22 and 8 Figure lD shows a convex surface 23.
9 The colors of these keyhoard buttons are tabulated below:
Character Button .
11 Fig. lA White Blue 12 Flg. la Black White 13 Fig. lC White Charcoal 14 Fig. lD White Charcoal 15 Fig. lE White Charcoal 1~ The method of producing characters embodying the invention 17 which is described is suitable for use with the buttons 18 illus-trated having flat or curved (convex or concave) surfaces 19 for characters and will produce the colored characters.
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.~ 20 Figures 2 and 3 illustrate the diversity of characters .~: .
21 required on keyboard buttons, the former showing characte~s 22 required for Germany, Greece, Hungary and Hong Kong while the 23 latter shows characters for E`arsi, Mathematical, Technical and 24 Copperplate Gothic. All the characters shown may be produced ~ 25 by embodiment of the invention.
-, 26 Referring now to Figure 4 showing the steps in a process 27 to deposit characters on blank keyboard buttons. The first 28 step in the process is to feed blank bu-ttons in bulk into a 29 well-known automatic load and feed Stage 1. Suitable button :: .
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~0B13901 1 materials are acrylonitrile butadiene styrene (ABS) or s-tyrene 2 acrylonitrile (SAN). ~ach keyboard button type as shown in 3 Fiyure 1 has a separate hopper as ls well-known, and the 4 controls of the stage are preset to feed buttons from a desired hopper to a conveyor. During transfer to the conveyor, each 6 button is oriented so that the surface 21, 22 or 23 ~Figure 1) 7 is generally horizontal.
8 In Stage 2, the horizontal surface of each button is 9 chemically cleaned removing dirt and grease to ensure consistent surface quality. This stage may consist of mechanical scrubbers 11 and solvent or detergent sprays. Any liquid sprayed on the 12 surface will be allowed to evaporate before further processing.
13 This stage may include an etch of the horizontal surfaces to 14 provide improved adherence of the subsequent deposited layer.
Next, the clean, dry button surface is coated with a 16 radia-tion sensitive material at Stage 3. Photo-sensitive 17 chemlcals are well known in the electronics art and are 18 commercially available from many chemical manufacturing 19 companies. They are commonly known as photo-resist materials and have the property of produciny a layer which af-ter exposure 21 to light is insoluble/soluble (in accordance with its positive 22 or negative characteristic of the particular resist used) to 23 a selected developing solution but soluble/insoluble when not 24 exposed. Photo-resist materials used in the semiconductor art are usually transparent and are used as a temporary etch resist 26 layer after exposure to permit selective etchingi they are 27 themselves subsequently removed by a further etch.
28 In a first embodiment of the present invention, a self 29 colored photo sensitive emulsion is used whose color is unchanged '.
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~ 8901 1 by exposure to light so the original color of the er.ulsion is the 2 color of characters depositecL by the process. The photo 3 sensitive emulsion is sprayed over the horizontal bu-tton surface ~- 4 to provide a layer of substantially uniform thickness.
. Next, the buttons on the conveyor pass through a tunnel oven 6 in Stage 4 to dry the layer c>f photo sensitive emulsion. In the 7 following Stage 5, each keyboard button wi-th a horizontal suri.ace 8 coated with a photo sensitive layer is exposed to a li~ht image 9 of a selected keyboard button character.
A suitable optical projection system is shown in Flyure S.
11 A lamp 30 produces a horizontal divergent beam of li~3ht 31 which 12 passes through a heat filter 32 to a condenser lens 33 to form a 13 converging beam 34. The lamp is selected to emit radiation in 14 regions of the spectrum to which material is sensitive, usually :
15 the blue and ultraviolet regions. This beam of light is reflected 16. by mirror 35 to the vertical and focussed by reduction lens 32 to 17 illuminate surface 21 of keyboard button 37. ~ shutter 38 enables . 18 the exposure time to be selected. A slide 39 is adjacent to 19 condenser lens 35 and the optical system is arranged to focus a 20 character on the slide at the surface 21 of keyboard button 37.
- 21 Slide 39 contains a character represented by a transparent/
; 22 opaque portion and forms a mask for a character. The optical.
23 system is desicJned so that a sufficiently shar~ image of the 24 character on slide 39 is provided on surface 21 which may be flat or curved as previously described with reference to Fig. 1.
26 Thus, a latent image of a required character having a sufficiently 27 well-defined edge is formed in the photo sensitive layer on 28 surface 21.

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Character slide 39 is selected from a character slide 2 library 40 and positioned under automatic control 41. Character 3 . slide library 39 holds character slide 39 for all required 4 characters and enables quick changes of characters. Control 41 is a computer which in addition monitors and controls the 6 lamp 30 and exposure time. Figures 2 and 3 illustrate a few 7 of the characters required on keyboard buttons.

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8 Thus, keyboard buttons leave Stage 5 with a latent exposed 9 image of a character and are taken by the conveyor to Stage 6 in which the characters are developed. In Stage 6 the button 11 is chemically developed by a spray which removes only portions of ~12 the photo sensitive layer on surface 21 leaving the desired 13 character formed by a colored layer of exposed photo sensitive 14 material.

Then the conveyor takes developed keyboard buttons carrying 16 characters for drying at Stage 7 in a tunnel oven for coating 17 with a transparent protective lacquer such as polyurethane varnish 18 in Stage 8. A lacquer must be selected to have no reaction with 19 either the keyboard buttons or the character. The protective layer over a character on surface 21 provides an abrasion 21 resistant layer to prevent character wear during use of the 22 keyboard buttons.

23 Finally, Stage 9 is a tunnel oven for drying the protective 24 lacquer followed by an automatic unload from the conveyor into hoppers for completed keyboard buttons.

26 In the embodiment already described, a self colored photo 27 sensitive materia:L was used. This self coloring may be due to 28 colored pigment present ln the initial photo sensitive emulsion 29 whose color is unchanged during processing. Alternatively, the desired color may be produced by a chemical change as in , . . .
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1 conventional color photography in the photo-sensi-tive material 2 during exposure to radiation at Stage 5 to produce a colored 3 character image.
4 Another alternative is to use a developing solution which removes unexposed photo sensitive material and at the same time 6 colors the exposed latent image of a character, ei-ther by dying 7 or by chemical action.
8 A last alternative for producing a colored character is to 9 include an additional Stage after Stage 5 in which -l:he developed ;-character image is sprayed by a color dye to provide a desired 11 optimum color.
12 The optical projection system shown in Figure 5 may be 13 repiaced by a scanning system in which exposure of the sensitive 14 layer is carried out by a moving light spot, a moving laser beam or a moving beam of other radiation with which the sensi-tive 16 layer may be exposed. A data processing system stores the 17 required characters as scan data which is accessed to generate 18 a scan to expose a desired character.
19 While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it 21 will be understood by those skilled in the art that various 22 changes in form and details may be made therein witnout 23 departing from the spirit anci scope of the ~nvention.
~ What is claimed is:

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A keyboard button manufacturing process for depositing characters on keyboard buttons comprising steps of:
orienting blank keyboard buttons in an array with the surface thereof on which a character is to be deposited in a predetermined orientation;
cleaning said surface of each said button;
coating said cleaned surface of each said button with a layer of radiation sensitive material;
exposing said surface of each said button to radiation to provide a latent image in the form of a selected character;
developing said exposed layer of said radiation sensitive material to provide the selected character; and coating each said character bearing surface of said button with a transparent protective layer.

2. The process as described in Claim 1, in which:
said radiation sensitive material is self-colored.

3. A process as described in Claim 1, wherein:
said exposing and developing steps produce a color change in said radiation sensitive material.

4. A process as described in Claim 2, wherein:
said exposing and developing steps produce a color change in said radiation sensitive material.

Claims 1, 2, 3, and 4-

5. The process as described in Claim 1, wherein:
said developing of said exposed layer includes coloring each so developed character.

6. The process as described in Claim 1, further including:
dying each said character after developing with a color dye.

7. A process as described in Claim 1, in which:
said step of exposing comprises optically projecting a selected character image onto said layer of radiation sensitive material.

8. A process as described in Claim 2, in which:
said step of exposing comprises optically projecting a selected character image onto said layer of radiation sensitive material.

9. A process as described in Claim 3, in which:
said step of exposing comprises optically projecting a selected character image onto said layer of radiation sensitive material.

10. A process as described in Claim 4, in which:
said step of exposing comprises optically projecting a selected character image onto said layer of radiation sensitive material.

-Claims 5, 6, 7, 8, 9 and 10-

11. A process as described in Claim 5, in which:
said step of exposing comprises optically projecting a selected character image onto said layer of radiation sensitive material.

12. A process as described in Claim 6, in which:
said step of exposing comprises optically projecting a selected character image onto said layer of radiation sensitive material.

13. A process as described in Claim 1, in which:
said step of exposing comprises selectively scanning said surface having said radiation sensitive layer with a beam of radiation.

14. A process as described in Claim 2, in which:
said step of exposing comprises selectively scanning said surface having said radiation sensitive layer with a beam of radiation.

15. A process as described in Claim 3, in which:
said step of exposing comprises selectively scanning said surface having said radiation sensitive layer with a beam of radiation.

-Claims 11, 12, 13, 14, and 15-

16. A process as described in Claim 4, in which:
said step of exposing comprises selectively scanning said surface having said radiation sensitive layer with a beam of radiation.

17. A process as described in Claim 5, in which:
said step of exposing comprises selectively scanning said surface having said radiation sensitive layer with a beam of radiation.

18. A process as described in Claim 6, in which:
said step of exposing comprises selectively scanning said surface having said radiation sensitive layer with a beam of radiation.

19. A keyboard button comprising:
a blank keybutton substrate having a surface on which a character may be deposited, a residual layer of exposed and developed radiation sensitive material bearing the image of a desired character, said layer being on said surface; and a transparent protective layer coating over each said character bearing surface.

-Claims 16, 17, 18 and 19-